1. Field of the Invention
The present invention relates to formulations of gelled lysozyme, achieved by the addition of water to a lysozyme suspension in a solvent, such as an alcohol. In fact, it was surprisingly discovered that lysozyme itself is a gelling substance (self-gel) and, therefore, it can be advantageously formulated into topical compositions without the addition of other gelling substances such as cellulose, starch or other polysaccharides. The activity of the lysozyme is enhanced as compared to other formulations comprising lysozyme. The formulations contained in the present invention are useful in the fields of therapeutics, disinfectants, sanitizers, personal hygiene, and cosmetics for human and veterinary use.
2. Description of Related Art
“Lysozyme”, also known as muramidase, is part of the innate immune system and is intended as a family of enzymes that catalyze the hydrolysis of mucopolysaccharides that form the cellular wall of bacteria, causing their lysing. The term “lysozyme” includes lysozymes of natural origin, like the one present in hen-egg-white and many other animal species, but also synthetic lysozymes and recombinant lysozymes, like human recombinant lysozyme. Lysozyme is widely present in the animal and plant kingdoms, in particular in algae, bacteria, fungi and certain metazoa. In humans it is present in various physiological fluids, tissues and organs such as milk, saliva, placenta, spleen, leukocytes, tears, serum, etc, where it performs fundamental functions such as part of the immune function in the protection from infections. Industrially, lysozyme is often obtained by extraction from hen-egg-whites as free base or as an organic or inorganic salt, preferably as a hydrochloride. Lysozyme, free-base or in a hydrochloride form, is soluble in water. The resulting solution does not show particular rheological properties as, for example, significant viscosity values. Lysozyme base or hydrochloride is practically insoluble in common organic solvents, like ethanol, methanol, dioxane, mercaptoethanol or isoamyl alcohol (see below).
TABLE 1Solubility of lysozyme in various organic solvents.Solubility/Solubility/Solventmg ml−1μMCommentsAcetic acid0.5538.46clear supernatantAcetonitrile0.032.10clear supernatantBenzene0.021.40clear supernatantButanol0.032.10clear supernatantButyl chloride0.085.59clear supernatantChloroform0.2517.48clear sup., some(1% EtOH)dissolvedN-Dimethylformamide0.6142.66clear supernatantDimethyl sulfoxide>100>7000clear sup., all dissolvedDioxane0.021.40clear supernatantEthanol0.021.40clear supernatantFormic Acid>100>7000all dissolvedGlycerol>100>7000all dissolvedHeptane0.021.40clear supernatantIsoamyl alcohol0.085.59clear supernatant2-Propanol0.074.90clear supernatant2-Mercaptoethanol0.6545.45clear sup., somedissolved3-Mercaptopropionic4.20293.71clear sup., muchaciddissolvedMethanol0.010.70clear supernatant1-Propanol0.021.40clear supernatantTriethanolamine0.8855.94clear supernatantTrifluoroacetic acid>100>7000all dissolvedSource: Houen G, Acta Chemica Scandinavica, 1996 (50): 68-70